1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // UNSUPPORTED: c++03, c++11, c++14, c++17 10 11 // <type_traits> 12 13 // constexpr bool is_constant_evaluated() noexcept; // C++20 14 15 #include <type_traits> 16 #include <cassert> 17 18 #include "test_macros.h" 19 20 #ifndef __cpp_lib_is_constant_evaluated 21 #if TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) 22 # error __cpp_lib_is_constant_evaluated should be defined 23 #endif 24 #endif 25 26 // Disable the tautological constant evaluation warnings for this test, 27 // because it's explicitly testing those cases. 28 #if TEST_HAS_WARNING("-Wconstant-evaluated") && defined(__clang__) 29 #pragma clang diagnostic ignored "-Wconstant-evaluated" 30 #endif 31 32 template <bool> struct InTemplate {}; 33 34 int main(int, char**) 35 { 36 #ifdef __cpp_lib_is_constant_evaluated 37 #ifdef TEST_COMPILER_MSVC 38 #pragma warning(push) 39 #pragma warning(disable: 5063) // 'std::is_constant_evaluated' always evaluates to true in manifestly constant-evaluated expressions 40 #endif // TEST_COMPILER_MSVC 41 // Test the signature 42 { 43 ASSERT_SAME_TYPE(decltype(std::is_constant_evaluated()), bool); 44 ASSERT_NOEXCEPT(std::is_constant_evaluated()); 45 constexpr bool p = std::is_constant_evaluated(); 46 assert(p); 47 } 48 // Test the return value of the builtin for basic sanity only. It's the 49 // compiler's job to test the builtin for correctness. 50 { 51 static_assert(std::is_constant_evaluated(), ""); 52 bool p = std::is_constant_evaluated(); 53 assert(!p); 54 ASSERT_SAME_TYPE(InTemplate<std::is_constant_evaluated()>, InTemplate<true>); 55 static int local_static = std::is_constant_evaluated() ? 42 : -1; 56 assert(local_static == 42); 57 } 58 #ifdef TEST_COMPILER_MSVC 59 #pragma warning(pop) 60 #endif // TEST_COMPILER_MSVC 61 #endif // __cpp_lib_is_constant_evaluated 62 return 0; 63 } 64